Class IX SEBA Science – Chapter 7: Diversity in Living Organisms
Class IX SEBA Science – Chapter 7: Diversity in Living Organisms
🌍 1. What is the Basis of Classification?
- Classification helps in organizing living organisms into groups.
- Basis of classification:
- Cell structure (prokaryotic or eukaryotic)
- Body organization (unicellular or multicellular)
- Mode of nutrition (autotroph or heterotroph)
- Presence or absence of cell wall
- Habitat and reproduction
🦠 2. Classification and Evolution
- Evolution is the process by which newer forms of organisms have evolved from older ones.
- Classification also shows evolutionary relationships.
- Lower organisms (e.g., bacteria) are more ancient than higher ones (e.g., mammals).
🧬 3. The Hierarchy of Classification Groups
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Mnemonic: King Philip Came Over For Good Soup
🧫 4. Five Kingdom Classification (By R.H. Whittaker)
a) Monera
- Unicellular, prokaryotic
- Cell wall present (in some)
- Examples: Bacteria, blue-green algae
b) Protista
- Unicellular, eukaryotic
- Some have cilia or flagella
- Examples: Amoeba, Paramecium
c) Fungi
- Multicellular (mostly), eukaryotic
- Heterotrophic, cell wall of chitin
- Reproduce by spores
- Examples: Yeast, mushroom
d) Plantae
- Multicellular, eukaryotic
- Autotrophic, cell wall of cellulose
- Examples: Algae, ferns, flowering plants
e) Animalia
- Multicellular, eukaryotic
- No cell wall, heterotrophic
- Examples: Insects, fish, mammals
🌱 5. Classification of Plantae
a) Thallophyta
- Simple body, no roots/stems/leaves
- Example: Spirogyra
b) Bryophyta
- Small, non-vascular, have root-like and leaf-like parts
- Live in moist soil
- Example: Moss
c) Pteridophyta
- Have roots, stems, leaves; vascular
- Do not produce seeds
- Example: Fern
d) Gymnosperms
- Naked seeds, cones
- Example: Pine
e) Angiosperms
- Seeds enclosed in fruits
- Have flowers
- Divided into:
- Monocots (one seed leaf): maize
- Dicots (two seed leaves): mango
🐾 6. Classification of Animalia
a) Porifera
- Pore-bearing, simplest animals, no tissues
- Example: Sponges
b) Coelenterata (Cnidaria)
- Have cavity and tentacles
- Example: Hydra
c) Platyhelminthes
- Flat worms, bilateral symmetry
- Example: Planaria
d) Nematoda
- Round worms, body unsegmented
- Example: Ascaris
e) Annelida
- Segmented worms, closed circulatory system
- Example: Earthworm
f) Arthropoda
- Jointed legs, exoskeleton
- Example: Insects, spider
g) Mollusca
- Soft body, often with shell
- Example: Snail
h) Echinodermata
- Spiny skin, radial symmetry
- Example: Starfish
i) Chordata
- Have notochord (some have backbone)
- Subgroups:
- Pisces: Fish
- Amphibia: Frogs
- Reptilia: Lizards, snakes
- Aves: Birds
- Mammalia: Humans, dogs
📘 Exercise Questions and Answers
1. Why do we classify organisms?
To simplify study and understand the similarities and evolutionary relationships among organisms.
2. Give three examples of the range of variations found in living beings.
- Size: Microorganisms to blue whale
- Structure: Unicellular to multicellular
- Habitat: Water, land, air
3. Which do you think is more basic: similarity in body design or in function?
Similarity in body design is more basic as it indicates common ancestry and helps in classification.
4. Who proposed the five kingdom classification?
R.H. Whittaker in 1969.
5. What are the major divisions in Plantae?
- Thallophyta
- Bryophyta
- Pteridophyta
- Gymnosperms
- Angiosperms
6. How are Angiosperms classified?
- Monocots: One cotyledon (e.g., rice)
- Dicots: Two cotyledons (e.g., bean)
7. How do Porifera differ from Coelenterata?
- Porifera: No body cavity, no tissues
- Coelenterata: Have cavity and tissues
8. Which organisms have notochord?
Organisms of Phylum Chordata, such as fish, birds, mammals.
✍️ Extra Important Questions with Answers
1. What is taxonomy?
The science of classifying organisms is called taxonomy.
2. What are the three main features used to classify organisms?
- Cell type (prokaryotic/eukaryotic)
- Body structure (unicellular/multicellular)
- Mode of nutrition (autotrophic/heterotrophic)
3. Why are algae placed in Thallophyta?
Because they have simple body structure without true roots, stems, or leaves.
4. What is the notochord?
A flexible rod-like structure present in chordates that supports the body.
5. Why are mammals considered the most advanced animals?
Because they have complex organs, give birth to young ones, and nourish them with milk.
continue to Chapter 8: Motion?
